I can't explain what might cause super-brightness, but I don't think it's necessary to leave the CC sitting for a day in order to safely dicharge the CRT. Every compact Mac from about the SE/30 onward has a bleeder resistor that quickly discharges the high voltage stuff when it's turned off. If you're paranoid, you can be double-safe if you also use the "screwdriver under the suction cup" technique that's standard for the Mac Plus and earlier compacts. I was very nervous about this the first time I did it, but it's quite simple and I've now done it dozens of times without electrocuting myself.